Composite Header Steam Heat Exchanger for Thin-Film Condensation
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Solution Overview
Problem
Existing steam heat exchangers face issues with filmwise condensation, including high thermal resistance due to thick liquid films, inefficient gas-liquid separation, complex piping structures, and increased installation difficulty, which affect heat exchange efficiency and occupy a large area.
Innovation Solution
A steam heat exchanger with a composite header system, featuring a single header divided into two sections, connected by a transition pipe, and incorporating bypass and balance pipes to manage pressure differences and facilitate gas-liquid separation, reducing film thickness and turbulence to enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If filmwise condensation is used in a single-stage heat exchanger, then the structure is simple, but the heat exchange coefficient is low due to thick liquid film
Solution Approach 1:
The heat exchanger is divided into multiple stages with separate inlet and outlet headers for each stage. The liquid film is discharged from each stage independently through separate discharge pipes, creating multiple condensation zones. This segmentation reduces the liquid film thickness in each stage and improves the heat exchange coefficient while maintaining structural manageability.
2Productivity
If multiple heat exchangers are connected in series with intermediate liquid discharge, then the heat exchange coefficient increases, but the piping structure becomes complex and occupies large area
Solution Approach 1:
Multiple heat exchanger stages are integrated into a single compact unit with a unified shell and chamber structure. The inlet and outlet headers are positioned at the same level, and liquid discharge pipes are arranged vertically, eliminating the need for extensive external piping connections. This merging reduces the occupied area and simplifies the overall piping structure while maintaining multi-stage condensation functionality.
3Productivity
If intermediate liquid discharge is implemented, then condensation is accelerated, but gas-liquid separation becomes difficult due to pressure drop
Solution Approach 1:
Each heat exchanger stage has its own independent liquid discharge pipe connected to a dedicated liquid outlet header, creating localized liquid discharge zones. This local quality approach ensures that liquid is discharged from each stage separately without creating significant pressure drops that would hinder gas-liquid separation. The uniform distribution of liquid discharge points maintains stable flow conditions and improves separation efficiency.
4Ease of operation
If liquid outlet headers are independent with pressure drop, then liquid discharge is facilitated, but foamy liquid flows into steam inlet header affecting heat transfer
Solution Approach 1:
The liquid discharge system is segmented into separate discharge paths for each heat exchanger stage, with each stage having its own liquid outlet header and discharge pipe. This segmentation prevents foamy liquid from one stage from flowing into the steam inlet header of another stage, as each stage operates independently. Liquid discharge is facilitated without compromising the heat transfer effect of subsequent stages.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composite header system improves heat exchange efficiency by reducing film thickness, simplifies piping, and reduces installation complexity, while effectively managing pressure differences for improved gas-liquid separation and compact design.
Implementation Method 1
heat exchange tubes or heat exchange plates... exchange heat with a cooling medium
Implementation Method 2
steam... is condensed by a main condenser... excess steam and condensed water enter a main pipe
Implementation Method 3
condensation heat transfer of steam in a tube (plate) pass... phase change heat (latent heat) released during condensation
Implementation Method 4
phase change heat (latent heat) released during condensation must pass through the liquid film
Implementation Method 5
a cooling wall surface is always covered by a liquid film... accelerate condensation... flow of a fluid in a heat exchange piping
Implementation Method 6
pressure drop between the two... under the action of a pressure drop, some foamy liquid flows into the steam inlet header
Data Source
Figure 1
AI summary
The present invention relates to a steam heat exchanger, comprising a composite header, wherein a first-stage steam inlet header and a second-stage steam inlet header are arranged above the composite header, and the composite header is in communication with the second-stage steam inlet header by means of a transition pipe; and further comprising two groups of heat exchange tubes or heat exchange plates, wherein inlet and outlet ends of a first group of heat exchange tubes or heat exchange plates are respectively connected to the first-stage steam inlet header and the composite header, and inlet and outlet ends of a second group of heat exchange tubes or heat exchange plates are respectively connected to the second-stage steam inlet header and the composite header. According to the present invention, a steam flow rate in a first-stage heat exchange tube and in a heat exchange plate (tube) pass along a flow direction of a condensation liquid is increased, the discharge speed of a condensation liquid film is accelerated, the thickness of the condensation liquid film is greatly reduced, and turbulence in the condensation liquid film is caused, so that the heat exchange efficiency in a first group of heat exchange plate (tube) pass is greatly improved. According to the present invention, the piping structure comprising the header is significantly simplified, and a secondary pipeline connection between heat exchanger groups is reduced. Thus, the processing and assembly of the pipeline structure are more convenient.